關於使用session過濾器實現登錄攔截

 

首先在web.xml中配置，配置方法與字符攔截器大同小異，配置如下：

  

<!-- 使用filter實現登錄控制 -->
    <filter>
        <filter-name>SessionFilt</filter-name>
        <filter-class>com.ed.web.admin.action.LoginFilter</filter-class>

        <init-param>
            <param-name>encoding</param-name>
            <param-value>utf-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>SessionFilt</filter-name> 
        <url-pattern>要攔截的頁面</url-pattern>
    </filter-mapping>

   和普通過濾器配置沒什么區別，就是多了兩個初始化參數，兩個參數的作用分別是：
        encoding----->用來指定一個具體的字符集
        forceEncoding------->Spring的早期版本這個參數作用很單一，當request中已經被指定了一個字符集的時候是否再將用 endcoding對應的字符集設置到request中去。舉個例子來說明，假如說過濾器就像上面 那樣被配置到web.xml了，當請求 被提交之后，過濾器會判斷request.getCharacterEncoding()是否為null，如果是null那么就會進行 request.setCharacterEncoding("UTF-8")的操作，如果不是null那么過濾器什么也不會做。

      看下攔截后的具體邏輯：

       

public class LoginFilter implements Filter {
    private String excludedPaths;
    private String [] excludedPathArray;
    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }
    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        HttpServletRequest request = (HttpServletRequest)arg0;
        HttpServletResponse response = (HttpServletResponse)arg1;
        HttpSession session = request.getSession();
        //需要放行的路徑
        if( request.getRequestURI().indexOf("/admin/login")!= -1
            ||request.getRequestURI().indexOf("/pac/ky")!= -1
                ||request.getRequestURI().indexOf("/pac/yh")!= -1
                ||request.getRequestURI().indexOf("/pac/yn")!= -1
                ||request.getRequestURI().indexOf("/pac/yn")!= -1){
            arg2.doFilter(arg0, arg1);
        }
        else{
            if(session.getAttribute("loginUser")==null   ){
                response.sendRedirect(request.getContextPath()+"/timeout.jsp");
            }else {
                arg2.doFilter(arg0, arg1);
            }
        }
    }
    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
    }
}